Manufacture of synthetic yarns



P 1942- J. s. McL ELLAN I 2,294,995

MANUFACTURE OF SYNTHETIC YARNS Filed Nov. 21, 1959 JoH/v 5. Madam/v INVENT OR BY u.

ATT NE YS vicinity of the spinneret.

Patented Sept. 8, 1942 MANUFACTI JRE SYNTFETIC YARNS John S. McLellan, Kingsport, Tenn., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application November 21, 1939, Serial No. 305,523 i ,2 Claims.

This invention relates to'a process for producing synthetic yarns such as those composed of cellulose organic derivatives including cellulose acetate, cellulose propionate, cellulose acetate propionate, cellulose acetate butyrate, and the like, and more particularly to an improved method for controlling the tensile strength and cross-sectional characteristics of such yarns.

It has been found that cellulose organic derivative yarns of superior tensile strength and im- In the following examples and description, I have set forth several of the preferred embodiments of my invention, but they are included proved cross-sectional characteristics may be obtained by maintaining the temperature of the atmosphere in the spinning cell in proximity to the spinneret at a relatively low value. I

The present invention has as an object to pro-' vide a simple and effective method for coolingthe atmosphere of a spinning cell, particularly in the A further object is to provide a method of cooling the atmosphere surrounding the filaments in the vicinity of their point of extrusion continuously and without the introduction of currents of air-from outside the cell. A still further object is to provide a means for cooling the upper part of a spinning cell. and which is particularly adapted to accomplish cooling inthe dead end space of the so-called dead end type spinning cabinet. Another object is to provide a means whereby a direct and exact control of the temperature conditions in the vicinity of the spinneret may be constantly maintained. Other objects will appear hereinafter.

These objects are accomplished by the following invention which, in its broader aspects, comprises spinning cell is continuously conducted through- The effect obtained by the the water jacket. use of this device is to cool the filaments, thus raising their viscosity and wet strength, which in turn permits better orientation and an increased tensile strength of the ultimate yarn. An additionaler collateral effect of cooling the fllaments as indicated is to retard evaporation of the solvent and thus to permit simultaneous drafting and evaporation of solvent.

merely for purposes of illustration and not as a limitation thereof.

In the drawing;

Fig. 1 is a diagrammatic elevational view in partial section illustrating a, spinning cell equipped with a cooling device in accordance with my invention. i

Fig. 2 is a sectional view of Fig. 1 at right angles thereto, but in which the cooling device is not indicated in section.

Figs. 3 and 4 are sectional views of two types of cooling jackets,'both of which are designed to permit easy access to the spinneret.

Referring to Figs. 1 and2, the numeral I designates a dope main or manifold through which an appropriate spinning solution, such as an acetone solution of cellulose acetate is supplied to a plurality of cabinets. The solution is conveyed from the main through conduit 2, the flow being controlled by valve 3 and given a predetermined pressure by means of pump 4 which forces the solution through candle filter 5 located in chamber 5 of spinning cabinet 1 and thence to spinneret B. The spinning solution in passing through the candle filter is heated to an appropriate temperature by means of a heated coil 9 through which an appropriate heating fluid continuously circulates.

As shown, the cabinet is provided at its lower portion with air inlet In and at its upper end outlet H, the latter being located at a distance approximately down from the top of the cabinet. The cabinet is also provided with a guide l2 and godet roll l3 over which the extruded filaments may pass on their way to an appropriate windup (not shown) or to further processing steps as may be desired. 7 a g In accordance with the invention, a cooling jacket I415 positioned at the top of the cabinet just slightly below 'the face of spinneret. This jacket is supplied with an appropriate cooling fluid, the fluid entering through inlet conduit l5 and being conveyed away through outlet conduit [6, as indicated by the arrows.

Assuming that the cooling fluid circulating" pass through the cylindrical space, whereupon it will come in contact with the warmer air outside the device, and become heated and rise in the annular space between the outer wall of jacket l4 and the inner wall of the spinning cabinet,

emerges from the spinneret in the form of filaments, with the results indicated above.

It will of course be evident that no hard and fast rules can be laid down with respect to the design of an apparatus suitable for carrying out the process of the instant invention, since such matters as the length and diameter of the jacket and the actual temperature of the cooling fluid will depend upon many conditions such as spinning solution temperature at extrusion, curing air temperature, heat losses through the cabinet wall, the quantity of heat radiated fromthe spinneret and candle filter assembly','the solvent concentration of the dope, the rate of extrusion and various other factors. My invention will be seen to reside in the provision of a process whereby 'the correct cooling tempera- ,ture may be maintained by means of constantly operative convection currents in the vicinity of the filaments at that portion of their travel where they contain appreciable amounts of solvent.

Inasmuch as this chimney effect is an important condition, the jacket should be designed to' obtain optimum circulation of air. In any event, the enclosed space defined by the inner walls of the jacket must be continuous so that objectionable leakage and cross currents are eliminated. If desired, the jacket may be extended to any desired-distance down the cabinet from the spinneret, this again being determined by the particular cooling conditions it is desired to maintain during the travel of the filaments from the top to the bottom of the cabinet.

In accordance with my invention, if the temperature of the spinning solution as it emerges from the spinneret isconstant, as will ordinarily be the case, I may maintain an atmosphere of substantially constant temperature in the immediate vicinity of the filaments by continuously supplying the cooling jacket with a cooling fluid maintained at an appropriate temperature. By

determining or controlling the temperature of both the spinning solution and the cooling fluid,

I am enabled to maintain a constant temperature As is well known in the art, provision must' be made for wiping or cleaning the face of the spinneret. Two forms of, cooling jackets which provide ready access 'to the spinneret are illustratedd'espectively, in Figs. 3and 4.

In Fig. 3, a duplex chamber arrangement is provided consisting of the semi-circular jacket I and hinged to a duplicate semi-circular jacket l1. as shown. The two sections are adapted to swing on hinge I8 which may be secured to the inner wall of the cabinet 8 in known manner. The sections may be fastened together in closed position by any appropriate device such as latch l9. In this form of jacket, it isnecessary to employ flexible tubing for the conduits 20 and 2| attached respectively to the sections H and I1 and to employ the same type of flexible outlet conduits at the top of the respective chambers, thus to provide for movement of the-sections with respect to the wall of the spinning cabinet. As will be apparent, when access to the interior of the device is necessary, all that is required is simply to unlatch the two sections and swing them apart on hinge l 8.

The device of Fig is in all respects similar to the jacket 14 of Figs. 1 and 2, except that instead of having a complete annular crosssection, provision is made for a void or opening 22 which is closed by hinged door 23 adapted to be fastened during use by means of latch 24.

.In this form of the device only one cooling fluid inlet 25 and a corresponding outlet (not shown) are employed. I

It will thus be seen that I have provided an extremely simple and eflicient method of cooling a spinning solution is extruded through a spine neret in the form of filaments first through a dead zone of relatively immobile evaporative medium and then into a current of evaporative medium passing counter-currently thereto, which comprises. causing a current of air cooled below the temperature of the spinning solution to circulate by convection in the dead zone in. a restricted space surrounding the immediate vicinity of the point of extrusion of and concurrently with thedirection of travel of the filaments.

2. A method of making filaments composed of I cellulose organic acid esters having improved properties of tensile strength and cross-sectional uniformity by the dry spinning method in which a spinning solution is extruded through a spinneret in the form of filaments first through a dead. zone of relatively immobile evaporative medium and then into a current of evaporative medium passing counter-concurrently thereto,

which comprises causing a current of air cooled below the temperature of the spinning solution to circulate by convection in the dead zone in a substantially circular path in the immediate vicinity of the point of extrusion of the filaments,

the down-going stream of air passing concurrently with the directionof travel of the filaments and in contact therewith for a portion of the travel of the filaments in the dead zone.

JOHN S. McLELLAN.

v cERT'IFIcA'nE 0F CORRECTION. Patent no. 2,2 h,995 September 8, 19!;2.

JOHN s. scLE LAn.

It is hereby certified that error appears in the twisted specification of the abeve numbered patent requiring correction asfollows: Page 2, seeondeolumn, line 59, claizn'z, for "counter-concurrently" read --c -.ountercurrently-'; and that .the said Letters Patent should be readwith this correction therein that the same may oenfom to the record 61 the case in the Patent O ffi'ce. I

Signed and sealed this 20th day of October, A. D. 1. 2.

Henry Van Arsdale, (3831) Acting Commissioner of Patents. 

